work on inheritance exercise

Author: Fithi-Teklom

sprint5-prep-exercises/inheritance.py

@@ -0,0 +1,67 @@
+class Parent:
+    def __init__(self, first_name: str, last_name: str):
+        self.first_name = first_name
+        self.last_name = last_name
+
+    def get_name(self) -> str:
+        return f"{self.first_name} {self.last_name}"
+
+
+class Child(Parent):
+    def __init__(self, first_name: str, last_name: str):
+        super().__init__(first_name, last_name)
+        self.previous_last_names = []
+
+    def change_last_name(self, last_name: str) -> None:
+        self.previous_last_names.append(self.last_name)
+        self.last_name = last_name
+
+    def get_full_name(self) -> str:
+        suffix = ""
+
+        if len(self.previous_last_names) > 0:
+            suffix = f" (previously {self.previous_last_names[0]})"
+
+        return f"{self.first_name} {self.last_name}{suffix}"
+
+
+person1 = Child("Sara", "Ali")
+
+print(person1.get_name())
+print(person1.get_full_name())
+
+person1.change_last_name("Ahmed")
+
+print(person1.get_name())
+print(person1.get_full_name())
+
+
+person2 = Parent("Sara", "Ali")
+
+print(person2.get_name())
+
+# These lines would cause errors because these methods
+# only exist in Child, not Parent:
+
+# print(person2.get_full_name())
+# person2.change_last_name("Ahmed")
+
+print(person2.get_name())
+
+# This would also cause an error:
+# print(person2.get_full_name())
+
+
+# The important inheritance relationship is:
+
+# Parent
+#   │
+#   ├── get_name()
+#   │
+#   ▼
+# Child
+#   ├── inherits get_name()
+#   ├── adds change_last_name()
+#   └── adds get_full_name()
+
+# So a Child can use the inherited Parent method, but a Parent cannot use methods that only exist in Child.